Valve-unloading mechanism



R. N. EHRHARTL VA'LVE UNLOADING MECHANISM. APPLICATION FILED NOV. 6. 1917.

1,352,439, PatentedSept. 14, 1920.

N} n v 73 Condenser" INVENTOR.

AT'TORNEKS.

UNITED STATES PATENT. OFFICE.

RAYMONDN. EI-IRHART, or Enenwoon lE'ARK, PENNSYLVANIA, ASSIGNOR To WEST- INGHOUSE ELECTRIC & MANUFACTURING 00., A oonronn'rrou or rENNsYLv NIA.

VALVE-UNLOADING MECHANISM.

pa e Patented Sept; 14, 1920.

Application filed November 6,1917. Serial No. 200,627.

To all whom it may concern:

Be it known that I, RAYMOND N. EHRIIART, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have made a new and useful Invention in Valve-Unloading Mechanism, of which the following is a specification.

This invention relates to valve unloading mechanisms and has for an object to produce a mechanism for unloadingor partially unloading a relief, valve. 1

A further object is to produce a new and improved mechanism for preventing a building up of pressure in a condenser or other apparatus beyond a predeterminel pressure.

A further objectis to produce a relief valve and actuating mechanism which takes the place of two or more other relief valves and which serves to protect the apparatus with which it is employed from dangerous pressures.

A further object is to produce an improved operating mechanism for a relief valve, which is capable of responding to different pressures at different parts of an apparatus and of thereby preventing the different parts of the apparatus from being subjected to excessive pressures.

A further object is toproduce a new and improved mechanism for opening a valve in response to a rise in pressure in a condenser or other vessel. 7

These and other objects are attained by means of apparatus embodying the features of my invention herein described and illustrated in the drawings accompanying and forming a part hereof.

In the drawings: Figure 1 is a diagrammatic view of 'a compound turbine installation, portions being shown in section for convenience of illustration.

Fig. 2 is a diagrammatic sectional view of a relief valve and unloading mechanism embodying the features of my invention.

Large turbine units frequently include two or more turbine sections, that is, the turbine is compounded or divided into separate high and low pressure sections. It is frequently necessaryto provide a relief valve in the receiver connecting'the high pressure section with the 'low pressure section so as to pre vent the low pressure section from being subjected to pressures in excess of those the low pressure turbine casing is designed to withstand. The maximum allowable pres sure within the receiver isusually greater than atmospheric pressure, consequently if the vacuum is lost by the condenser and no I means are provided for discharging to the atmosphere the steam exhausted from the low pressure turbine section, thepressure in the condenser soon rises to substantially thepressure existing in the receiver. If the condenser is of the surface type an internal pressure greater than atmospheric pressure is objectionable on account ofthe large size of the condenser shell; and if the condenser is of the jet type such a pressure is objectionable because the steam would force its way through the condensate pump into the discharge tunnel Where it might cause serious water-hammers Therefore it is customary or at least desirable to also provide a relief valve in the connection between the low pressure section and the condenser and to set this valve to-open at a pressure considerably lower than the pressure at which-the relief valve of the receiver opens. With large size turbines these valves must be so large that they are quite expen sive and frequently are difficult to install because of the amount of space required.

In Fig. 1, I have illustrated a turbine installationincluding a high pressure turbine section 5, a low pressure turbine section 6, connected to the high pressure section by means of a receiver 7,.anda condenser 8 of the jet type into which the low pressure section exhausts. A relief valve 9 is adapted to relieve excessive pressure in the receiver 7 and therefore in the low pressure turbine section 6, and a second relief valve 10 is adapted to similarly protect the condenser 8' from excessive pressures; The discharge pump 11, of the condenser 8, discharges into a discharge tunnel 12, which is protected from water hammer by the relief valve 10. It will, of course, be understood that the relief valve 10 is set to open at a pressure lower than that required to open the valve 9.

My invention contemplates a valve mechanism which may be employed in connection with an installation such as that illustrated in Fig. 1 for the purpose of eliminating the necessity of employing the relief valve 10 in the exhaust line from the low pressure turbine section. I accomplish this bycausing the relief'valve, of the receiver 7, to serve the double purpose of protecting the turbine section 6 against excessive pressures, under ordinary operating conditions, and of protecting the condenser against excessive pressures in case the condenser loses its vacuum. In the illustrated embodiment of the invention this accomplished by unloading or partially unloading the relief valve 9 in case the pressure in the condenser exceeds a determined mes-sure. For example, the valve 9 may be adjusted to open in response to a pressure in the receiver of 15 pounds above atmosphere, under normal operating conditions, or a pressure of 2 pounds above atmospheric pressure, under abnormal. pressure conditions within the condenser S.

In Fig. 2, I have illusti ued in detail a hydraulically loaded valve 9, which may advantageously be employed in connection with the receiver 7 of the apparatus illustrated in Fig. is shown, the valve 9 is provided with a valve dish 13, which is adapted to control communication between an inlet port Ll and an outlet port 15 and which is normally held against its seat by hydraulic or other fluid pressure acting on a piston 16. Tl e port 14: is adapted to communicate with the receiver '1' and the port 15 with the atmosphere. The piston 16 is connected to the valve disk 13 by means of a valve stem 17 and is adapted to operate in a cylinder 18 which is shown as mounted on the valve 9.

Water or any other fluid under pressure is admitted to the cylinder 18 a, *e th piston 16 through a conduit 19, for the pur pose of counterbalancing the pressure ad mitted to the lower side of the dish 13 through the port 141. The pressure in the cylinder 18 is adjusted to maintain the valve closed until the pressure in the receiv r exceeds a determined pressure. By varying the fluid pressure on the piston 16, the valve may be adjusted to open at practically any desired pressure of the fluids on the inlet side oI the valve.

I have also illustrated a mechanism which may be employed for varying the pressure on the piston 16 in response to a rise in pressure within the condenser. As shown, a cylinder 20 is connected by means of a conduit 21 to the condenser in which it desired to keep the pressure below a relatively low limit. A piston 22 is provided in the cylinder 20 and is subjected on one side to the relatively low pressure transmitted to the upper end of the cylinder 20 by the concuit 21 and on the other side to atmospheric pressure admitted to the lower part of the cylinder by an open port As shown. a spring 24 is inserted between the piston 22 and the upper end of the cylinder 20 and opposes the torzi-e of the atmospheric pressure on the lower side of the piston. I have illustrated a piston rod 25 which extends from. the piston 22 out through the upper end oi. the cylinder hen the piston 22 is in the upper end of the cylinder 20, this stem engages one arm 26 of a bell crank 27, the other arm 28 of which is normally adapted to hold closed a valve 29. This valve is shown in the end of the conduit 30 which is connected with the cylinder 18 so that when itis opened it relieves or par tially relieves the hydraulic or fluid pressure on the piston 16. A spring 31 tends to lift the arm 28 and openthe valve 29, but the arm is normally held in a valve closing posh tion by the engagement of the arm 26 with the piston rod 25. I have also shown a spring 32 between the arm 28 and the valve 29 for insuring the correct seating of the latter.

In operation the piston rod 25 is normally held in engagement with the arm 26 of the bell crank 27 by the unliialanced atmospheric pressure acting on the piston 22. If the condenser loses its vacuum the pressure above the piston 22 increases and this pressure plus the force of the spring 24 overcomes the pressure of the atmosphere on the lower side of the piston 22, and moves the rod 25 out of engagement with the arm 26. This releases the bell crank 27 and permits the valve 29 to open in response to the hydraulic pres sure within the conduit 30. The opening of the valve 29 relieves the hydraulic pressure n the piston 16 and permits the valve 9 to open in response to a relatively low pressure within the receiver.

s shown in the drawings, the conduit 19 is provided with an orifice 33 which restricts the flow of fluids into the cylinder 18. The

valve 29 and the conduit 30 are so propor' tioned that they are capable of carrying away the fluid taster than the conduit 19 is capableor. delivering it, consequently the pressure of the fluid on the piston 16 is decreased so that fluid of relatively low pressure, for example, 2 pounds per square inch, may open the valve 9. By varying the proportions of the apparatus illustrated the valve 9 may be made to open at practically any desired pressure.

Vhile I have described and illustrated but one embodiment of my invention, it will be apparent to those skilled in the art that arious changes, modifications, substitutions, additions and omissions may be made in the apparatus illustrated without departing from the spirit and scope of the invention, as set forth by the appended claims.

What I claim is:

1. In a fluid operated power developing system, a pressure actuated relief valve for the system adapted to be opened by pressure in the system when the pressure in the vicinity of the said valve exceeds a determinedamount, and means controlled by the pressure in a remote part of the system for causing the valve to open at a pressure less than the determined pressure.

An apparatus for relieving the pressure in a system, the maximum limit of pressure in two parts of the system being different, a valve loaded to. relieve the higher pressure at its maximum limit, and means for unloading the valve in response to a rise of the lower pressure to its maximum limit.

3. In an apparatus for relieving pressures at different maximum limits, a loaded pressure relief valve, and means responsive to the pressure at one maximum limit for varying the load on the valve a definite amount to cause the valve to relieve the pressure at that limit.

a. In a valve unloading mechanism, a loaded valve for normally relieving the pressure of a fluid at a predetermined limit, and means responsive to another predetermined limit of pressure of the fluid for changing the loading of the valve a predetermined amount, so as to relievethe pressure at the last mentioned limit.

5. In combination with a power developing system, means for relieving pressure in one part of the system at a predetermined limit and means responsive to a different predetermined pressure limit in another part of the system for varying the limiting pressure required to open the relieving means.

6. In combination with a power developing system, a loaded relief valve for relieving pressures in one part of the system at a predetermined limit, and means responsive to a different limiting pressure in an other part of the system for changing the load on the relief valve a predetermined amount.

7. In combination with a relief valve, a piston for controlling the valve, means in dependent of the pressure controlled by the valve for maintaining a definite fluid pressure against said piston so as to load. the valve, and means responsive to a limiting pressure for varying the fluid pressure on the piston so as to change the loading of the valve.

8. An apparatus for relieving fluid pressure in a system, a relief valve normally loaded by fluid at a predetermined pressure so as to be opened by the greater of two limiting pressures, means for reducing the pressure of the loading fluid a predetermined amount so that the valve is opened by the lesser of the two limiting pressures, and means responsive to the lesser limiting pressure for controlling said last mentioned means. i a

9. In a power developing system, a high pressure turbine, a low pressure turbine, a receiver for delivering motive fluid from the high pressure turbine to the low pressure turbine, a loaded relief valve communicating with said receiver for preventing the pressure in the receiver from building up beyond a predetermined limit, a condenser for receiving and condensing the motive fluid discharged by the turbines, and means responsive to a rise of pressure in the condenser for reducing the loading of the relief valve.

7 10. In a turbine installation, a turbine, a condenser connected thereto, means for relieving excessive pressures in the turbine, and means responsive to a rise of pressure in the condenser for changing the pressure limit at which the relieving means acts.

11. In a turbine installation, high and low pressure turbine sections connected by a receiver, a condenser serving the turbine, means for relieving excessive pressures in the receiver, and means responsive to an excessive pressure in the condenser for causing the relieving means to relieve the pressure in the receiver at a lower limit. I

12. In a power developing system, a prime mover, a condenser associated therewith, means for relieving pressures in the prime mover at a predetermined limit, and means responsive to a change of pressure in the condenser for changing the pressure limit at which the relieving means operates.

13. In a fluid operated power developing system having units operating under different pressures, a relief valve for the system in communication with the regions of different pressures and adapted to be opened normally to relieve the pressure in the system by a determined pressure in the vicinity of the relief valve, and means controlled by the pressure in the part of the system operating at a lower pressure for causing the valve to open at a pressure less than the determined pressure.

In testimony whereof, I have hereunto subscribed my name this 5th day of November, 1917.

RAYMOND N. EHRHART. Witness O. W. McGrmn. 

